摘要
苹果是最受人们欢迎的水果之一,其种植面积和产量逐年增加,但目前采摘主要由人工完成,并且作业期长、劳动强度大,而随着人口的老龄化和农业劳动力的减少,研究采摘机器人代替人工完成苹果采摘作业十分必要。但是由于苹果本身的特性及其形态的限制,到目前为止国内外的苹果采摘的自动化程度仍然很低,本课题针对以上的问题,提出研究适用于苹果采摘作业的末端执行器。
末端执行器作为机器人与外界环境互相作用的最后执行部件一直受到研究人员的关注。除了传统的刚性驱动和执行机构以外,本课题组研究的新型气动柔性驱动器FPA(Flexible Pneumatic Actuator),既是驱动器也是执行器,可以直接构成各种关节,以此为基础设计了气动柔性弯曲关节,但由于橡胶管易变形,弯曲关节在载荷方向会产生扭曲变形。本文在弯曲关节原有结构的基础上,加强了关节的侧向刚度。由三个弯曲关节组成的末端执行器在保持一定柔性的同时也兼顾了刚度,工作时向弯曲关节气动柔性驱动器FPA内充入压缩气体,实现末端执行器的运动。主要研究内容:
(1)对采摘对象苹果进行了基本的力学特性的研究,利用万能电子试验机,完成苹果压缩试验与苹果果柄剪切试验,分析讨论了它们的特性关系;
(2)设计了基于气动柔性驱动器FPA的新型弯曲关节,用力学分析的方法对弯曲关节进行建模,分析建立关节弯曲量及输出力与其内腔气体压力之间的数学关系,搭建了实验平台,完成弯曲关节转角实验与弯曲关节输出力实验,实验结果表明,理论分析与实际结果相一致;
(3)研制了一种基于气动柔性驱动器FPA的末端执行器,建立了末端执行器抓取苹果目标的数学模型,对末端执行器抓持方式进行了研究比较;
(4)分析了磨削式、旋转剪切式和直线剪切式三种果枝分离机构,并分别对其进行了实验研究,其中旋转剪切式果枝分离机构结构简单、控制方便,作为本文设计的末端执行器果枝分离机构;
(5)搭建了末端执行器的实验平台,进行实验研究,该末端执行器有较大的输出力,并具有很好的柔顺性,满足苹果的抓取任务需求。最后设计了集成控制系统,并
分析了苹果采摘机器人的整个控制流程。
本文基于气动柔性驱动器FPA的研制了新型的弯曲关节并应用于采摘末端执行器的抓持机构,结合旋转剪切式果枝分离机构研制苹果采摘末端执行器的原型样机及其控制系统,实验表明该末端执行器能够完成对苹果的抓取和果枝分离任务。
Apple is one of the most popular fruits, the planting area and yield of apple is increasing year by year. But the manual picking of the operation, the long period of operation and big labor intensity restrict the apple industrialization greatly. With the aging population and agricultural workforce reduction, it is necessary to develop apple harvesting robot to execute the process of harvesting, instead of human. However, due to apple's own characteristics and forms of restrictions, the roboticized level of picking apples at home and abroad is still very low. In order to resolve the problem, a kind of end-effector which is suitable for apple-picking is proposed in this thesis.
As final executing manipulator for robot to interact with outside environment, the end-effector has been paid much attention. Besides the traditional rigid driving and executing devices, the new type flexible pneumatic actuator FPA, developed by our researching group, is a kind of actuator as well as manipulator. Different joints can be designed using FPA. Because of the high deformability of rubber, the bent joint in the load direction will produce distortion. In this thesis, the lateral stiffness is enhanced based on the original bending joint structure. The end-effector formed by the three bending joints, not only maintains certain flexibility, but also takes into account the stiffness. Inflating compressed gas into the FPA achieves the end-effector movement. The whole work is as follows:
(1) Researching the basic mechanical characteristics of the apple, using universal electronic testing machine, the completion of apple compression and apple stems shear test, discussed the characteristics of their relationship;
(2) A new type of bending joints was developed based on flexible pneumatic actuator.
The relationship between pressure and bending capacity was analyzed. The experimental platform was built to complete the joint angle bending and output force experiments, whose results show that experimental curve matches with the theoretical curve well;
(3) A new type of end-effector was developed based on flexible pneumatic actuator. The grasping apple's mathematical model of end-effector was established. And the grasping apple model was compared and analyzed.
(4) The grinding, rotary shearing and linear cutting fruit-branch separating models are analyzed and the experimental results show that the rotary shearing model has virtues of simply structure and easy to be controlled. The rotary shearing model was taken as the fruit-branch separating structure for the end-effector.
(5) Building experimental platforms for the end-effector. The force of the end-effector is quite strong, and the actuator can grasp apples perfectly and flexibly. Designing the integrated control system, and analyzing the controlling process of the entire apple picking robot.
In this dissertation, the end-effector and its controlling system was developed based on flexible pneumatic actuator, bending joint and rotary shearing fruit-branch separating structure. Experiments show that the end-effector can be a good completion of apple's grasping and fruit-branch separating task.
引文
[1] Ceres R, Pons J L, Jiménez A R, et al. Design and implementation of an aided fruit-harvesting robot (Agribot) [J]. Industrial robot,1998,5(5): 337-346.
[2]张立彬,计时鸣,胥芳,等.农业机器人的主要应用领域和关键技术[J].浙江工业大学学报,2002,30(1): 36-41.
[3] Caldwell D G, Medrano-Cerda G A and Goodwin M J. Braided Pneumatic Actuator Control of a Multi-Jointed Manipulator [A], IEEE Int. Conf on Systems, Man and Cybernetics Proceedings, Le Touquet, France, 1993: 423–428.
[4] Ching-Ping Chou, Black Hannaford. Static and Dynamic Characteristics of McKibben Pneumatic Artificial Muscles [A], IEEE Conf. on Robotics and Automation, San Diego, USA, May 1994, 281-286.
[5] Ching-Ping Chou, Black Hannaford, Measurement and Modeling of McKibben Pneumatic Artificial Muscles [J], IEEE Transaction on Robotics and Automation, 1996, 12(1): 90-102.
[6] Ozkan M, Inoue K, Negishi K, et al. Defining A Neural Network Controller Structure for a Rubbertuator Robot, Neural Networks, 2000, 13: 533-544.
[7] Boblan I, Bannasch R, Schwenk H, et al. A Human-Like Robot Hand and Arm with Fluidic Muscles: Biologically Inspired Construction And Functionality, Embodied Artificial Intelligence, 2004, 3139: 160-179.
[8] http://www.shadow.org.uk/
[9] Suzumori K, Iikura S, and Tanaka H. Flexible Microactuator for Miniature Robots [A], Proc. IEEE Micro Electro Mechanical Systems Conf., Nara, Japan, 1991, 204–209.
[10] Koichi Suzumori, Shoichi Likura, hiroshisa Tanaka. Development of Flexible Microactuator and Its Applications to Robotic Mechanisms [A], Proceedings of the 1991 IEEE International Conference on Robotics and Automation, Sacramento, California, April 1991, 1622-1627.
[11] Koichi Suzumori, Toshihiro Maeda, Hiroshi Watanabe, Toshiaki Hisada, Fiberless Flexible Microactuator Designed by Finite-Element Method [J], IEEE/ASME Transactions on Mechatronics, 1997, 2(4): 281-286.
[12] Toshiro Noritsugu, Mitsuhiko Kubota, Sadaharu Yoshimatsu. Development of Pneumatic Rotary Soft Actuator Made of Silicone Rubber [J], Journal of Robotics and Mechatronics, 2001, 13(1): 17-22.
[13] Schulz S, Pylatiuk C, Bretthauer G. A New Ultralight Anthropomorphic Hand[C]// Proceedings of the 2001 IEEE International Conference on Robotics & Automation. Seoul, 2001:243722441.
[14] Caldwell D G, Medrano-Cerda G A and Goodwin M J. Braided Pneumatic Actuator Control of a Multi-Jointed Manipulator [A], IEEE Int. Conf on Systems, Man and Cybernetics Proceedings, Le Touquet, France, 1993: 423–428.
[15]鲍官军,气动柔性驱动器FPA的特性及其在多指灵巧手设计中的应用研究[D],浙江工业大学,2006.4: 13-19,79-80.
[16]杨庆华,张立彬,鲍官军等.气动柔性弯曲关节的特性及其神经PID控制算法研究.农业工程学报. 2004.7, 20(4): 88-91.
[17]赵匀,武传宇,胡旭东,等.农业机器人的研究进展及存在的问题[J].农业工程学报,2003,19(1): 20～24.
[18] Kondo N, Monta M, Fujiura T. Fruit harvesting robot in Japan [J]. Adv. Space Res. 1996, 18(1/2): 181～184.
[19]崔玉洁,张祖立,白晓虎.采摘机器人的研究进展与现状分析[J].农机化研究, 2007.2: 4-7.
[20] Van Henten E J, Van Tuijl B A J, Hemming J. Field test of an autonomous cucumber picking robot [J]. Biosystems Engineering,2003,86(3):305～313.
[21] Shigehiko Hayashi, Katsunobu Ganno, Yukitsugu lshii, et a1. Robotic harvesting system for eggplants [J]. JARQ. 2002. 36(3): 163～168.
[22] Murakami N, Inoue K, Otsuka K. Selective harvesting robot of cabbage [J]. JSAM, 1995, 2: 24～31.
[23] Reed J N, Miles S J, Butler J, et a1. Automatic mushroom harvester development[J]. J Agric EngngRes, 2001, 78(1): 15～23.
[24]周明镇,孙艾玲,动物的发展与人类起源[M],北京:科学出版社, 1978.
[25] Lim Mee-Seub, Oh Sang-Rok, Son Jaebum. A Human-Like Real-Time Grasp Synthesis Method for Humanoid Robot Hands [J], Robotics and Autonomous Systems, 2000, 30: 261–271.
[26] Ilhwan Kim, Nobuaki Nakazawa, Hikaru Inooka. Control of A Robot Hand Emulating Human’s Hand-over Motion [J], Mechatronics, 2002, 12: 55-69.
[27]张立彬,杨庆华,阮健,胥芳,气动关节人工手的研究[J],农业工程学报, 2003, 19(1): 84-86.
[28]管贻生,张启先,李泽湘,多指手操作:运动学算法和实验[J],机器人, 1998, 20(5): 321-332.
[29] Yung Hwan Yun, Hong Jun Eoh, Janghyeon Cho. A Two-Dimensional Dynamic Finger Modeling for the Analysis of Repetitive Finger Flexion and Extension [J], International Journal of Industrial Ergonomics, 2002, 29: 231-248.
[30] Mohamed Zribi, Jun Chen and Magdis.Mahmoud, Coordination and Control of Multi-fingered Robot [J],1999, 24: 125-149.
[31]姜力,刘宏,高晓辉,等.机器人灵巧手五维指尖力/力矩传感器的研究[J],机器人, 2000, 22(7): 730-733.
[32]张立彬,杨庆华,阮健,等.气动关节人工手的研究[J],农业工程学报,Vol. 19 No.1,P84-86,2003年1月.
[33]张立彬,杨庆华,鲍官军,等.一种气动柔性驱动器[P].中国, 200510049589.5. 2005.9.
[34] Yang Qinghua, Zhang Libin, Bao Guanjun. Research on Novel Flexible Pneumatic Actuator FPA, IEEE RAM'2004, 2004.12: 385-389.
[35]杨庆华,张立彬,阮健.气动弯曲关节的特性研究[J].工程设计学报, 2002, 9 (3): 159～161.
[36]杨庆华,张立彬,鲍官军,等.气动柔性弯曲关节的特性及其神经PID控制算法研究[J].农业工程学报,2004.7, 20(4): 88-91.
[37]李小昱,王为.苹果压缩特性研究[J].西北农业大学学报,1998.4, 26(2): 107～110.
[38]王荣,焦群英,高永毅.番茄力学特性的研究[J].农化机研究,2003. 10(4): 56～59.
[39]刘继展,李萍萍,李智国,等.面向机器人采摘的番茄力学特性试验[J].农业工程学报, 2008, 12(12): 66～70.
[40]王荣,焦群英,魏德强,等.葡萄的力学特性及有限元模拟[J].农业工程学报,2005,2(2): 7～10.
[41]王荣,焦群英,魏德强.葡萄与番茄宏观力学特性参数的确定[J].农业工程学报,2004,3(2): 54～57.
[42]李成,马小愚,雷溥.番茄果实力学特性及与成熟度关系的试验研究[J].农化机研究,2006, 1(1):167～169.
[43]吴家龙.弹性力学[M].北京:高等教育出版社,2001.
[44]吴德光,蒋小明.农产品压缩试验研究及应用[J].压缩试验方法.云南农业大学学报,1995, 5(3): 171～176.
[45] Arnold P C. Proposed techniques for axial compression tests on intact agricultural products of conrexshape. Trans ASAE [J], 1971, 14 (1) : 78～84.
[46] Mohsenin N N. Physical properties of plant and animal material. 2nded. New York: Gordon and Breach Science Pub[J], 1986. 154～169.
[47]杨明韶.农业流变学基础[M].呼和浩特:内蒙古农业大学自编教材. 2003, 8: 1～100.
[48] Stanley D W. Biological membrane deterioration and associated quality losses in food tissues[J]. CRC Crit Rev Food Sci Nutr, 1991(30): 487 ~553.
[49] L.R.G.Treloar. The physics of rubber elasticity [M]. New York: Oxford University Press, 2005.
[50]李建藩,气压传动系统动力学[M],广州:华南理工大学出版社,1991.
[51]田中久裕,液压与气动的数字控制及应用[M],重庆:重庆大学出版社,1992.
[52] Austruamicrosystems AG. AS5045 Data Sheet. http://www.austriamicrosystems.com/
[53] LIU H, lberall T, Bekey G. The multi-dimensional quality of task requirements for dectrous robot hang control[A].Proceedings of the IEEE Conference on Robotics and Automation[C],1989.
[54] Stansfield S A. Robotic grasping of unknown objects, a knowledge based approach [J].International Journal of Robotics Research, 1991, 10(4): 314~316.
[55] Miller A T, Knoops S, Christensen H I, Allen P K. Automatic grasp planning using shape primitives[A].Proceedings of IEEE International Conference on Robotics and Automation[C], 2003: 1824~1829.
[56]熊蔡华,熊有伦,杨叔子.机器人多指收抓取中的规划问题[J].机器人,1995, 17(1).
[57] Stansfield S A. Knowledge-based robotics grasping[A]. Proceedings of the IEEE Conference on Robotics and Automation[C], 1990.
[58] Microchip Technology Inc. dsPIC30F4011/4012 datasheet. dsPIC30F Family Reference Manual, 2007.
[59]何礼高. dsPIC30F电机与电源系列数字信号控制器原理与应用[M].北京:北京航天航空大学出版社, 2007.